WOOTON AND STANDLEY FLORA OF NEW MEXICO. 165 



There are several well-marked groups of closely-related species, the most conspicuous 

 of which is that clustered about Q. gambelii, including Q. utaJmisis, Q. submollis, Q. 

 gunnisonii, Q. vreelandii, Q. novomexicana, and Q. leptophylla, all of which have 

 green deciduous leaves of much the same texture and outline with varying degrees of 

 pubescence. Another group is that consisting of shrubs of small or large size (never 

 forming trees) of the higher moimtains, having more or less persistent blue green 

 leaves — Q. undulata, Q. fendleri, Q. rydhergiana. Yet another well-marked group 

 contains the low trees of the southern part of the State, occurring among the rocks 

 and canyons of the drier and hotter mountains. These are Q. grisea, Q. arizonica, and 

 Q. reticulata, the last being a large tree in the mountains of New Mexico. A single 

 chestnut oak, known from two stations, is Q. muhlenbergii, a most unexpected find. 



The affiliations of the other species are not so easily seen, each species standing 

 more or less by itself in New Mexico. 



Acorns of the different oaks were formerly used by the Indians as food. They were 

 boiled or roasted or sometimes dried and ground into flour. 



KEY TO THE SPECIES. 



Acorns sericeous-tomentose inside, maturing the second year 1. Q. hypoleuca. 



Acorns not sericeous-tomentose inside, maturing the first year. 

 Leaves bluish, grayish, or yellowish green (never bright 

 chlorophyll green), more or less coriaceous, mostly 

 persisting until the appearance of new leaves, hence 

 the plant leafy all the time. 



Leaves not persisting; medium-sized shrub 2. Q. fendleri. 



Old leaves persisting till after the appearance of the 

 young ones; shrubs or trees. 

 Mature plants shrubs, never trees. 



Plant about 1 meter high, with very small 



acorns and leaves 4. Q. rydhei-giana. 



Plants more than a meter high, the leaves and 

 acorns large. 



Leaves fulvous beneath; cup turbinate G. Q. turbinella. 



Leaves not fulvous beneath; cup hemis- 

 pheric. 

 Leaves only moderately coriaceous, 

 neither spinulose-toothed nor 



crisped 3. Q. undulata. 



Leaves strongly coriaceous, much 



crisped and spinulose-toothed. . . 5. Q. pungens. 

 Mature plants trees (shrubby forms immature, 

 usually not fruiting). 

 Scales of the cup thin, only slightly corky- 

 thickened on the back; mature leaves 

 yellowish green. 

 Leaves of the same color on both surfaces. . 7. Q. emoryi. 

 Leaves fulvous beneath, especially when 



yoxmg 8. Q. ivilcoxii. 



Scales of the cup corky- thickened on the back; 

 leaves fulvous beneath, glabra te above. 

 Acorns large; mature leaves all more or less 

 conspicuously toothed (resembling 

 those of Q. fendleri) 9. Q. confusa. 



